Table 1. Baseline Characteristics of the Overall Population Contributing to the Safety Analysis and of the Population Contributing to the Primary Efficacy End Point Analysis.*.
| Variable | Overall Safety Population† | Seronegative Efficacy Population‡ | ||||
|---|---|---|---|---|---|---|
| Total (N=2021) |
Placebo (N=1010) |
Vaccine (N=1011) |
Total (N=1467) |
Placebo (N=717) |
Vaccine (N=750) |
|
| Male sex — no. (%) | 1142 (56.5) | 568 (56.2) | 574 (56.8) | 838 (57.1) | 397 (55.4) | 441 (58.8) |
| Median age (IQR) — yr | 30 (24–40) | 30 (24–39) | 31 (24–40) | 31 (24–41) | 31 (24–41) | 31 (24–41) |
| Age category — no. (%) | ||||||
| 18 to <45 yr | 1695 (83.9) | 852 (84.4) | 843 (83.4) | 1206 (82.2) | 593 (82.7) | 613 (81.7) |
| 45 to <60 yr | 283 (14.0) | 133 (13.2) | 150 (14.8) | 223 (15.2) | 102 (14.2) | 121 (16.1) |
| ≥60 yr | 43 (2.1) | 25 (2.5) | 18 (1.8) | 38 (2.6) | 22 (3.1) | 16 (2.1) |
| Body-mass index — no. (%)§ | ||||||
| 0 to <18.5 | 151 (7.5) | 68 (6.7) | 83 (8.2) | 119 (8.1) | 50 (7.0) | 69 (9.2) |
| 18.5 to <25 | 1021 (50.6) | 521 (51.6) | 500 (49.6) | 752 (51.4) | 371 (51.7) | 381 (51.0) |
| 25 to <30 | 456 (22.6) | 221 (21.9) | 235 (23.3) | 330 (22.5) | 156 (21.8) | 174 (23.3) |
| ≥30 | 390 (19.3) | 200 (19.8) | 190 (18.8) | 263 (18.0) | 140 (19.5) | 123 (16.5) |
| Current smoker — no. (%) | 849 (42.0) | 415 (41.1) | 434 (42.9) | 644 (43.9) | 304 (42.4) | 340 (45.3) |
| Consumes alcohol on a weekly basis — no. (%) | 990 (49.0) | 501 (49.6) | 489 (48.4) | 729 (49.7) | 365 (50.9) | 364 (48.5) |
| Health worker — no. (%) | 167 (8.3) | 88 (8.7) | 79 (7.8) | 144 (9.8) | 80 (11.2) | 64 (8.5) |
| Race — no. (%)¶ | ||||||
| Black African | 1421 (70.5) | 708 (70.3) | 713 (70.6) | 949 (64.9) | 453 (63.4) | 496 (66.2) |
| Mixed | 300 (14.9) | 149 (14.8) | 151 (15.0) | 251 (17.2) | 128 (17.9) | 123 (16.4) |
| White | 259 (12.8) | 132 (13.1) | 127 (12.6) | 231 (15.8) | 119 (16.7) | 112 (15.0) |
| Other | 37 (1.8) | 18 (1.8) | 19 (1.9) | 32 (2.2) | 14 (2.0) | 18 (2.4) |
| Hypertension — no. (%) | 56 (2.8) | 25 (2.5) | 31 (3.1) | 42 (2.9) | 20 (2.8) | 22 (2.9) |
| Chronic respiratory condition — no. (%) | 62 (3.1) | 26 (2.6) | 35 (3.5) | 53 (3.6) | 22 (3.1) | 31 (4.1) |
| Diabetes — no. (%) | 9 (0.4) | 5 (0.5) | 4 (0.4) | 5 (0.3) | 3 (0.4) | 2 (0.3) |
| Median time between doses (IQR) — days | 28 (28–32) | 28 (28–32) | 28 (28–32) | 28 (28–32) | 28 (28–32) | 28 (28–32) |
| Median follow-up period since randomization (IQR) — days | 156 (140–171) | 156 (140–171) | 156 (140–171) | 161 (143–172) | 160 (142–172) | 161 (143–174) |
| Median time since second injection (IQR) — days | 121 (114–143) | 121 (114–142) | 121 (114–143) | 122 (114–143) | 122 (114–142) | 128 (114–143) |
| Person-days of follow-up since randomization | 290,394 | 143,962 | 146,432 | 229,129 | 111,471 | 117,658 |
| Person-days of follow-up since second injection | 228,506 | 113,063 | 115,443 | 184,595 | 89,714 | 94,881 |
IQR denotes interquartile range.
The overall safety population included all participants who received at least one dose of vaccine or placebo, irrespective of baseline serologic status suggestive of past SARS-CoV-2 infection or positive results on nucleic acid amplification testing within 96 hours before randomization and on the day of randomization. Five participants who were randomly assigned to a trial group but never received an injection of placebo or vaccine were excluded.
The seronegative efficacy population included all participants in the vaccine efficacy analysis for the primary end point who had a negative nucleic acid amplification test within 96 hours before randomization and on the day of randomization and tested negative for SARS-CoV-2 N-protein IgG.
The body-mass index is the weight in kilograms divided by the square of the height in meters. In both the overall safety population and the seronegative efficacy population, data on body-mass index were missing for 3 participants, all of whom were in the vaccine group.
Race was reported by the participants. In both the overall safety population and the seronegative efficacy population, data on race were missing for 4 participants, 3 in the placebo group and 1 in the vaccine group.